Treatment of exfoliative cutaneous lupus erythematosus in a German shorthaired pointer dog with mycophenolate mofetil.

BACKGROUND: Immune-modulating drugs show limited therapeutic efficacy in canine exfoliative cutaneous lupus erythematosus (ECLE); over half of ECLE dogs are eventually euthanized for their lack of response to therapy. OBJECTIVE: To describe a case of generalized ECLE in a dog in which mycophenolate mofetil (MMF) treatment achieved complete remission. ANIMAL: A 3-year-old, male castrated German shorthaired pointer was presented with a three months history of generalized scaling, erythematous macules and plaques, follicular casts and hypotrichosis affecting the head, trunk, ventrum and medial aspects of all limbs. The dog exhibited lameness and stiff gait. METHODS AND MATERIALS: Complete blood count, serum chemistry profile, urinalysis, serum antinuclear antibody test, histopathological examination and RT-qPCR of skin biopsies. RESULTS: Histologically, skin biopsy specimens revealed lymphocyte-rich interface dermatitis, infundibular interface mural folliculitis and periglandular lymphocytic infiltrate. The absence of systemic signs and unremarkable laboratory tests excluded concurrent systemic lupus erythematosus. Treatment of ECLE was initiated with oral MMF (22 mg/kg, twice daily). Within three weeks of starting MMF therapy, a marked improvement in lameness and a moderate decrease in erythema and scaling was observed. After four months, erythema, scaling and follicular casts had completely resolved, and at the time of writing the dog's ECLE remains in complete remission with twice daily MMF (10 mg/kg). The lesional skin transcriptome revealed predominant T helper 1 (Th1) lymphocytic inflammatory response with strong upregulation of interferon pathway. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge, this is the first reported case of successful treatment of ECLE with MMF as a single-agent therapy.